70 lines
1.8 KiB
Python
70 lines
1.8 KiB
Python
"""
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HX720/HX711
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Micropython library for the HX720/HX711(Load Cell)
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=======================================================
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@dahanzimin From the Mixly Team
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"""
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import time
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from machine import Pin
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from micropython import const
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DATA_BITS = const(24)
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READY_TIMEOUT_SEC = const(500)
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class HX720:
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def __init__(self, sck_pin, dat_pin, scale=500, pulse_obj=1):
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self._sck = Pin(sck_pin, Pin.OUT, value=0)
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self._dat = Pin(dat_pin, Pin.IN, Pin.PULL_UP)
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self._obj = min(max(pulse_obj, 1), 3)
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self.scale = scale
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self.tare()
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def _wait(self):
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"""超时响应报错"""
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star = time.ticks_ms()
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while not self.is_ready():
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if time.ticks_diff(time.ticks_ms(), star) > READY_TIMEOUT_SEC:
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raise AttributeError("Cannot find a HX711/HX720")
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def is_ready(self):
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"""检查是否有数据可以读取"""
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return self._dat.value() == 0
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def set_scale(self, scale):
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"""设置比例因子"""
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self.scale = scale
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def read_raw(self):
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"""读取传感器的原始数据"""
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if not self.is_ready():
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self._wait()
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raw_data = 0
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for _ in range(DATA_BITS):
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self._sck.value(1)
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self._sck.value(0)
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raw_data = raw_data << 1 | self._dat.value()
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# 根据脉冲功能设置多读几次
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for _ in range(self._obj):
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self._sck.value(1)
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self._sck.value(0)
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return raw_data if raw_data < (1 << (DATA_BITS - 1)) else raw_data - (1 << DATA_BITS)
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def tare(self, times=10):
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"""清零传感器"""
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_values = []
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for _ in range(max(times, 5)):
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_values.append(self.read_raw())
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_values = sorted(_values)[2: -2]
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self.offset = sum(_values) / len(_values)
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def read_weight(self, times=5):
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"""读取重量数据，返回去掉偏移量的平均值"""
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_values = []
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for _ in range(max(times, 3)):
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_values.append(self.read_raw())
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_values = sorted(_values)[1: -1]
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return round((sum(_values) / len(_values)- self.offset) / self.scale, 2)
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